| 126 / | HD | STOVES AND FURNACES |
| 569 | DF | SOLAR HEAT COLLECTOR {18} |
| 572 | DF | .~ With control means energized in response to actuator stimulated by condition sensor {3} |
| 573 | DF | .~.~ Including sun position tracking sensor {7} |
| 579 | DF | .~.~.~ Fluid expansion sensor {1} |
| 580 | | .~.~.~.~ Gas |